According to movie, Taboulistan is small country situated between Afghanistan, Kyrgyzstan and Tajikistan. It's named after "tabbouleh", an Arab salad which they claim originates from Taboulistan. (More about the salad at Wikipedia.)

Here are a photo of the flag from the making of film, and a screenshot with more details of the flag. Also, a vertical variant of the flag is visible in this screenshot.

The flag is green-red-blue-red-green with an emblem in the middle. The emblem is yellow with tabbouleh in middle and the inscription: TABOUL. TÜMAT. PIRÇIL (above); SIBTIL MELÄCH (below).
Aleksandar Nemet, 4 August 2013

It should be noted that despite looking like Turkish, it's actualy phonetically based on the French words for:

TABOULEH. TOMATO. PARSLEY.

SUBTLE MIX

Marc Pasquin, 5 August 2013